From 665e433697247c4a43e055830dee7a72afdb810f Mon Sep 17 00:00:00 2001
From: Amlal El Mahrouss <amlal@nekernel.org>
Date: Thu, 1 Jan 2026 12:52:28 +0100
Subject: feat: FIX Checksum API for OCL.FIX.

Signed-off-by: Amlal El Mahrouss <amlal@nekernel.org>
---
 CMakeLists.txt                         |  2 ++
 example/fix_tag_example/CMakeLists.txt |  2 +-
 example/fix_tag_example/example.cpp    |  5 +++-
 include/ocl/fix/checksum.hpp           | 43 +++++++++++++++++++++++++++++++++-
 test/fix_basic/fix.test.cpp            |  2 +-
 5 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 343aee1..1829925 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,6 +7,8 @@ find_package(Boost REQUIRED)
 
 add_library(ocl_fix src/fix/parser_impl.cpp)
 target_link_libraries(ocl_fix boost_core)
+
+install(DIRECTORY include/ DESTINATION include)
 install(TARGETS ocl_fix DESTINATION lib)
 
 set_property(TARGET ocl_fix PROPERTY CXX_STANDARD 20)
diff --git a/example/fix_tag_example/CMakeLists.txt b/example/fix_tag_example/CMakeLists.txt
index 57bec7a..56afa24 100644
--- a/example/fix_tag_example/CMakeLists.txt
+++ b/example/fix_tag_example/CMakeLists.txt
@@ -12,4 +12,4 @@ add_executable(FixExample example.cpp)
 
 set_property(TARGET FixExample PROPERTY CXX_STANDARD 20)
 target_include_directories(FixExample PUBLIC ../../include/ocl)
-target_link_libraries(FixExample PRIVATE Boost)
+target_link_libraries(FixExample PRIVATE ocl_fix)
diff --git a/example/fix_tag_example/example.cpp b/example/fix_tag_example/example.cpp
index f7f3e76..ac4f479 100644
--- a/example/fix_tag_example/example.cpp
+++ b/example/fix_tag_example/example.cpp
@@ -1,4 +1,5 @@
 #include <ocl/fix/parser.hpp>
+#include <ocl/fix/checksum.hpp>
 
 constexpr char default_fix[] = {
 	'8', '=', 'F', 'I', 'X', '.', '4', '.', '2', 0x01,
@@ -15,7 +16,7 @@ constexpr char default_fix[] = {
 
 int main(int argc, char** argv)
 {
-	ocl::fix::visitor basic_visitor;
+	ocl::fix::visitor	   basic_visitor;
 	ocl::fix::range_buffer fix = basic_visitor.visit(default_fix);
 
 	ocl::io::enable_stdio_sync(false);
@@ -26,5 +27,7 @@ int main(int argc, char** argv)
 	ocl::io::print(":key=49\n");
 	ocl::io::print(":value=", fix["49"], "\n");
 
+	ocl::io::print("checksum=", ocl::fix::try_index_checksum(fix), "\n");
+
 	return 0;
 }
diff --git a/include/ocl/fix/checksum.hpp b/include/ocl/fix/checksum.hpp
index c075b13..31aee75 100644
--- a/include/ocl/fix/checksum.hpp
+++ b/include/ocl/fix/checksum.hpp
@@ -9,9 +9,50 @@
 #define __OCL_FIX_CHECKSUM
 
 #include <ocl/fix/detail/config.hpp>
+#include <ocl/fix/parser.hpp>
+#include <boost/core/detail/string_view.hpp>
 
 namespace ocl::fix
 {
-}
+
+	/// \brief Returns the checksum index of a FIX message.
+	/// \param range the range_buffer containing the message.
+	/// \throws runtime_error if the FIX message is invalid (missing tag "8").
+	inline std::string try_index_checksum(range_buffer& fix)
+	{
+		if (fix.is_valid())
+			return fix["10"];
+		else
+			detail::throw_runtime_error();
+	}
+
+	/// \brief FIX message operators namespace.
+	namespace operators::fix
+	{
+		using checksum_type = long long;
+
+		/// \brief Calculates the FIX protocol checksum for a message.
+		/// \param in_ Pointer to the message buffer.
+		/// \param len Length of the message in bytes.
+		/// \return The checksum value (sum of all bytes modulo 256).
+		inline checksum_type
+			checksum(const char* in_,
+				 const long  len)
+		{
+			if (len < 1)
+				return 0L;
+
+			long long cks{};
+
+			for (long idx{}; idx < len; ++idx)
+			{
+				cks += static_cast<unsigned char>(in_[idx]);
+			}
+
+			return cks % 256;
+		}
+	} // namespace operators::fix
+
+} // namespace ocl::fix
 
 #endif
diff --git a/test/fix_basic/fix.test.cpp b/test/fix_basic/fix.test.cpp
index 82fb24c..43042b4 100644
--- a/test/fix_basic/fix.test.cpp
+++ b/test/fix_basic/fix.test.cpp
@@ -22,7 +22,7 @@ constexpr char default_fix[] = {
 	'1', '0', '=', '1', '4', '3', 0x01, 0x00 // CheckSum = 143
 };
 
-static ocl::fix::visitor		 basic_visitor;
+static ocl::fix::visitor	  basic_visitor;
 static ocl::fix::range_buffer fix = basic_visitor.visit(default_fix);
 
 TEST(FIXTest, FIXGoodPacket)
-- 
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